Evaluation of differential miRNA expression between Fusarium wilt-resistant and -susceptible watermelon varieties

Abstract

Watermelon (Citrullus lanatus) has been cultivated for nearly one thousand years and remains a commercially important crop. However, continuous planting often leads to the aggravation of many diseases. Watermelon Fusarium wilt (FW) is one of them, which is a fungal soil-borne disease caused by Fusarium oxysporum f. sp. niveum (Fon) that damages plant roots by invading vascular bundles. Therefore, it is imperative to comprehensively characterize the mechanism mediating disease resistance or susceptibility, as well as identify effective resistance genes, in order to breed improved disease-resistant watermelon varieties. miRNAs are endogenous non-coding RNAs that are widely involved in plant growth, development, metabolism, transport, stress response, and pathogen defense. However, there are few reports of disease-associated miRNAs, or their mechanisms of action, in Cucurbitaceae crops. In this study, the roots of both Fon-susceptible and resistant watermelon varieties were infected with GFP-labeled Fon. Three key infection time points were identified. Illumina sequencing was used to obtain Fon-resistance related miRNAs, and degradome sequencing was used to obtain miRNA target genes. A total of 23 differentially expressed miRNAs were identified at the three key infection time points, the degradation group sequencing found their only target gene. The results of this study provide a theoretical basis for studies of miRNA function and regulation during the interaction between Fon and watermelon plants and clues for the screening of watermelon resistance genes. In addition, this information can be used to breed disease-resistant watermelon varieties.